Most people are aware of Skype, though fewer are familiar with the fact that it now uses a centralized server which may be monitored by goverments, due to Microsoft's cooperation with the PRISM program by the NSA. A review of Ekiga has also been published.
Download Ekiga 4.0.1 (from Modem and Telephony Tools)20.5 MB | For Windows 7, Windows 8 / Vista / XP | Free